Using vti teaming to achieve load balance and redundancy

ABSTRACT

In an embodiment, a computer-implemented method for using virtual tunnel interface teaming to achieve load balance and redundancy in virtual private networks (“VPNs”) is disclosed. In an embodiment, a method comprises: receiving, by a gateway, configuration data from a control plane; based on the configuration data, configuring on the gateway a bonded virtual tunnel interface (“bonded VTI”) having a plurality of slave virtual tunnel interfaces (“slave VTIs”); configuring a plurality of VPN tunnels between the plurality of slave VTIs configured on the gateway and a plurality of slave VTIs configured on a remote gateway; configuring an IPsec VPN tunnel between the bonded VTI configured on the gateway and a corresponding bonded VTI configured on the remote gateway; logically combining the plurality of VPN tunnels into the IPsec VPN tunnel; and enabling communications of IPsec VPN traffic via the IPsec VPN tunnel.

BACKGROUND

Internet Protocol Security (“IPsec”) is a protocol suite used to securetransmissions of communications packets. The IPsec virtual privatenetworks (“VPNs”) are widely used to protect the packets as they travelover the Internet between datacenters, between datacenters and branchoffices, or between on-premises datacenters and public clouddatacenters. However, the designs of traditional IPsec processing thatcan only leverage a single core for a single IPsec tunnel are oftenunable to meet the increasing demands for the higher throughput andhigher packet transmission rates.

An edge gateway may offer IPsec VPN services implemented in virtualrouters. The IPsec services may be integrated with other services in thesame software-defined network offering. Examples of other services mayinclude packet routing, firewall, network address translation (“NAT”),load balancing, and service insertion.

The edges may support policy-based VPN and route-based VPN. Thepolicy-based VPN relies on a policy defined by, for example, a systemadministrator. In the policy-based VPN, the VPN configuration may bechanged only if the policy is changed. Thus, the policy-based VPN isdifficult to dynamically modify and scale up. In contrast, theroute-based VPN uses routing to decide which traffic needs to beprotected and directed to a virtual tunnel interface (“VTI”). Since theroute-based VPN supports dynamic routing protocols, it allows todynamically modify the definitions of the protected traffic, and thusprovides scalability.

VTI may be configured on a gateway and may be used to direct VPN trafficfrom the gateway to a VPN tunnel. The VTI, coupled with routing, canprovide scalability and high availability of the VPN services. The VTImay rely on static routing and dynamically provided routing informationto determine the traffic that should be protected and directed to theVPN tunnel.

The route-based VPN provides some benefits that are not provided by thepolicy-based VPN. For example, without reconfiguring the VPN, but basedon dynamically updated Border Gateway Protocol (“BGP”) configurationdata, the route-based VPN can dynamically modify the definitions of theprotected traffic. It also supports high availability via routing.

However, even the route-based VPN suffers from some performance issues.One of them is limited throughput. A packet sending gateway typicallyuses one VTI and one VPN tunnel to transmit the protected traffic. But,if the traffic directed to the VPN tunnel exceeds the tunnel capacity,then some packets are dropped as the tunnel's throughput is limited.

Other problems include CPU balancing issues. When a network interfacecard (“NIC”) implemented on a receiving gateway receives an encapsulatedpacket, it determines a hash value from the packet's outer headers (suchas L3-L4 headers) and uses the hash value to determine an Rx queue andselect a CPU for the packet. However, since different flows carriedthrough the same VPN tunnel have the same hash-based signature, a loadbalancer implemented on the receiving gateway keeps selecting the sameCPU for all packets. Thus, the selected CPU may become overloaded, whileother CPUs may remain under-utilized.

The route-based VPN also suffers from the lack of the VPN tunnelredundancy since a gateway uses only one VPN tunnel for all flows. If,for some reason, that VPN tunnel becomes nonoperational, then the VPNtraffic cannot be communicated with a remote site.

SUMMARY

In an embodiment, an interface-teaming approach for achieving loadbalance and redundancy in the IPsec-based VPN is described. The approachis implemented using the functionalities of the Layer 3 (“L3”) of theOpen Systems Interconnection (“OSI”) communications model. The approachincludes implementing multiple VTIs in a gateway to increase throughputand provide redundancy and logically combining the multiple VTIs into asingle teaming interface device.

From the perspective of the application layer (“L7” of the OSI), thegateway, for the VPN traffic, implements only a single teaminginterface, called a teaming interface device. However, from the L3perspective, the gateway implements multiple VTIs and multiplecorresponding VPN tunnels. As long as at least one of the VPN tunnels isavailable to the teaming device, the teaming device may forward the VPNtraffic to a remote gateway, and the upper-layer-protocol traffic may becommunicated without interruptions. Thus, the approach increasesthroughput and provides redundancy in the VPN tunnels establishedbetween the gateways.

In an embodiment, the interface-teaming approach supports theroute-based VPN which allows to dynamically update the VPN forwardingroutes and provide scalability. More specifically, based on the BGPconfiguration data, two gateways establish a BGP-over-IPsec sessionbetween themselves, and then an IPsec VPN tunnel that corresponds to theBGP-over-IPsec session. As new and updated routes are reflected in thedynamically updated BGP configuration data provided by the BGP, theprotected subnets are also updated, and the updated routing informationis used to modify the BGP-over-IPsec session.

In an embodiment, an IPsec VPN tunnel is established between a teaminginterface device implemented on one gateway of one datacenter and ateaming interface device implemented on another gateway of anotherdatacenter. A teaming interface device is also referred to as a bondedVTI device, or a bonded VTI. A bonded VTI is a virtual device and has anassigned IP address according to the configuration data provided for theBGP-over-IPsec session.

A bonded VTI implemented in a gateway may include a plurality of slaveVTIs configured on the gateway. While the bonded VTI is assigned an IPaddress, the corresponding slave VTIs do not have assigned IP addresses.One bonded VTI implemented on one gateway and another bonded VTIimplemented on another gateway may be two endpoints of the IPsec VPNtunnel.

From the perspective of the application layer, the IPsec VPN traffic istransmitted between a bonded VTI implemented on one gateway and a bondedVTI implemented on another gateway. However, the VPN traffic is actuallytransmitted between slave VTIs of one bonded VTI of one gateway andslave VTIs of another bonded VTI of another gateway.

To facilitate transmission of IPsec VPN traffic from a bonded VTIimplemented on a local gateway to a peer bonded VTI implemented on aremote gateway, a plurality of VPN tunnels is established between slaveVTIs of the bonded VTI of the local gateway and peer slave VTIs of thepeer bonded VTI of the remote gateway. A VPN tunnel, of the multiple VPNtunnels, is established between a local slave VTI of the bonded VTIconfigured on the local gateway and a peer slave VTI of the peer bondedVTI configured on the remote gateway.

To transmit a packet from a bonded VTI of a packet sending gateway to apacket receiving gateway, the bonded VTI of the packet sending gatewayrelays the packet onto a slave VTI that is selected from the multipleslave VTIs of the bonded VTI of the packet sending gateway.

A slave VTI may be selected based on a variety of approaches. Forexample, the slave VTI may be selected using a round-robin (“RR”)approach, a load balancing approach, and/or a hash-based approach. Ifthe hash-based approach is implemented, then a hash value is computedfrom the contents of inner headers of the packet. Since the hash valuescomputed from the content of the inner headers are most likely differentfor different packet flows, the hash-based approach allows selectingdifferent slave VTIs for different flows. This allows to load balancethe VPN tunnels established between the slave VTIs of the packet sendinggateway and the peer slave VTIs of the packet receiving gateway.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a block diagram depicting an example physical implementationview of an example logical network environment for realizing mechanismsfor using virtual tunnel interface teaming to achieve load balance andredundancy.

FIG. 2A is a block diagram depicting an example of multiple virtualprivate network tunnels established between two bonded devices.

FIG. 2B is an example process for selecting a slave virtual tunnelinterface of a bonded virtual tunnel interface device.

FIG. 3A is an example flow chart for configuring virtual private networktunnels.

FIG. 3B is an example flow chart for selecting, by a packet sendinggateway, a virtual tunnel interface and selecting a virtual privatenetwork tunnel.

FIG. 4 is an example flow chart for selecting, by a packet receivinggateway, a CPU for an IPsec VPN packet.

DETAILED DESCRIPTION

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the method described herein. It will be apparent,however, that the present approach may be practiced without thesespecific details. In some instances, well-known structures and devicesare shown in a block diagram form to avoid unnecessarily obscuring thepresent approach.

1. Example Physical Implementations

FIG. 1 is a block diagram depicting an example physical implementationview of an example logical network environment for realizing mechanismsfor using virtual tunnel interface teaming to achieve load balance andredundancy. In the depicted example, environment 10 includes adatacenter 11, a cloud environment 12, and an IPsec VPN tunnel 15. IPsecVPN tunnel 15 is established between a bonded VTI 31 of a gateway 110 ofdatacenter 11 and a bonded VTI 33 of a gateway 110A of cloud 12.Environment 10 also includes a physical network (not shown) andadditional elements such as routers and switches, some of which areshown in FIG. 1.

In an embodiment, IPsec VPN tunnel 15 is used to transmit VPN trafficbetween gateways 110-110A.

Datacenter 11 may include one or more gateways 110 and one or more hosts14. Gateway 110 may be configured to execute a datapath process 160, aload balancer process 150, a virtual router 140, and one or more virtualswitches 130. Host 14 may support one or more virtual machines (“VMs”)21, 201. Gateway 110 may implement one or more CPUs (not shown).

Cloud 12 may include one or more gateways 110A and one or more hosts14A. Gateway 110A may be configured to execute a datapath process 160A,a load balancer process 150A, a virtual router 140A, and one or morevirtual switches 130A. Host 14A may support one or more VMs 21A, 201A.Cloud 12 may implement one or more CPUs 1-3.

Datapaths 160-160A may be implemented as network stacks that comprisecollections of functional units configured to perform data processingoperations and arithmetic operations on packets.

Load balancer processes 150-150A may be implemented in virtual devicesconfigured in environment 10 to improve the distribution of workloadsand network traffic across communications tunnels and multiple computingresources.

Hosts 14-14A are computer devices configured to implement VMs, such asVMs 21-201 and 21A-201A, gateways 110-110A, virtual routers 140-140A,virtual switches 130-130A, and the like. The hosts may be referred to ascomputing devices, host computers, host devices, physical servers,server systems, or physical machines. The hosts may include hardwarecomponents such as commodity hardware computing platforms includingcomputing processors, memory units, physical network interface cards,and storage devices (not shown).

VMs 21-201 and 21A-201A are examples of virtualized computing instancesor workloads. A virtualized computing instance may include anaddressable data compute node or an isolated user space instance, oftenreferred to as a name space container.

1.1. Gateways

Gateways 110-110A comprise software that may be installed in a virtualmachine or on a physical server. Gateways 110-110A may be implemented asedge gateways and may be configured to provide network services such asdynamic host configuration protocol (“DHCP”) services, firewall, NAT,static routing, VPN, and load balancing. Gateways 110-110A may providenetwork edge security and gateway services to VMs 21-201 and 21A-201A.

Gateways 110-110A may be installed either as distributed routers or asservice gateways. Gateways 110-110A may be configured to connectisolated sub networks to shared networks. For example, gateways 110-100Amay be configured to transmit IPsec VPN traffic from datacenter 11 tocloud 12 via IPsec VPN tunnel 15.

1.2. Virtual Tunnel Interfaces

FIG. 2A is a block diagram depicting an example of multiple VPN tunnelsestablished between two bonded devices. In the depicted example, themultiple VPN tunnels comprise two VPN tunnels 44-54 that are logicallycombined into IPsec VPN tunnel 15 established between bonded VTI 31configured on gateway 110 and bonded VTI 33 configured on gateway 110A.Bonded VTI 31 has a VTI address 311, while bonded VTI 33 has a VTIaddress 331. Bonded VTIs 31-33 also establish a BGP-over-IP session (notshown) that corresponds to IPsec VPN tunnel 15.

In an embodiment, bonded VTI 31 logically combines slave VTIs 31A-31B,while bonded VTI 33 logically combines slave VTIs 33A-333B.

VPN tunnel 44 has two endpoints: one endpoint is configured with anunderlay VPN address 42 and another endpoint is configured with anunderlay VPN address 42A. In FIG. 2A, VTI 31A has underlay VPN address42, while VTI 33A has underlay VPN address 42A.

VPN tunnel 54 has two endpoints: one endpoint is configured with anunderlay VPN address 52 and another endpoint is configured with anunderlay VPN address 52A. In FIG. 2A, VTI 31B has underlay VPN address52, while VTI 33B has underlay VPN address 52A.

Virtual switches 130-130A (shown in FIG. 1) relay VPN packets ontoeither bonded VTIs 31 or 33, respectively, and thus onto IPsec VPNtunnel 15. However, virtual routers 140-140A (shown in FIG. 1) relay VPNpackets onto either slave VTIs 31A-31B or slave VTIs 33A- 33B,respectively, and thus onto either VPN tunnel 44 or VPN tunnel 54.

As new and updated routes are reflected in the dynamically updated BGPconfiguration data provided by the BGP, the BGP-over-IPsec session,established between bonded VTIs 31-33, and addresses of the bonded VTIsare also updated.

1.3. VPN Tunnels

Once a BGP-over-IPsec session is created between bonded VTI 31 andbonded VTI 33, IPsec VPN tunnel 15 between bonded VTIs 31-33 isestablished, and a plurality of slave VPN tunnels 44-54 is establishedbetween slave VTIs 31A-33A and VTIs 31B-33B, respectively. In otherimplementations, additional VPN tunnels may be established between theVTIs.

From the perspective of the upper-layer-protocols, the IPsec VPN packetsare routed via IPsec VPN tunnel 15 established between bonded VTI 31 andbonded VTI 33. However, using the presented VTI teaming approach, thepackets are actually routed via slave VPN tunnels 44-54 between slaveVTIs.

VPN tunnels 44 and 54 may be configured as active/active tunnels or asactive/slave tunnels. If they are configured as active/active tunnels,then load balancers 150-150A select one of the active tunnels from VPNtunnels 44-54. The selection may be made based on an outcome of anyselection algorithm. For example, the selection may be made based on ahash value computed from a 5-tuple (a source IP address, a destinationIP address, a source port, a destination port, a protocol identifier)included in an inner IP header of the packet and based on an outcome ofa RR/load balancing approach.

In an active/slave configuration, one VPN tunnel from a plurality of VPNtunnels 44-54 is active while the other VPN tunnel operates in a standbymode. If the active VPN tunnel becomes nonoperational, then the slavetunnel automatically becomes active. An active tunnel may be selectedfrom the slave tunnels based on the RR algorithm, a hash algorithm, orany other load balancing algorithm.

2. Configuring VPN Tunnels

FIG. 3A is an example flow chart for configuring virtual private networktunnels. In step 302, based on configuration data obtained from, forexample, a central control plane, a gateway configures a plurality ofslave VTIs on the gateway, and configures a plurality of slave VPNtunnels that back up the slave VTIs. Each of the slave VPN tunnels isassigned two underlay VPN addresses. Referring to FIG. 2A., VPN tunnel44 may have assigned underlay VPN address 42 at one endpoint andunderlay VPN address 42A at another endpoint, while VPN tunnel 54 mayhave assigned underlay VPN address 52 at one endpoint and underlay VPNaddress 52A at another endpoint.

If a dynamic route-based VPN is implemented, then gateways 110-110Aconfigure, in step 304, a BGP-over-IPsec session based on the BGPconfiguration data. The BGP configuration data may provide IP addressesfor bonded VTIs 31 and 33. Based on the BGP configuration data, gateways110-110A configure an IPsec VPN tunnel that corresponds to theBGP-over-IPsec session. Referring to FIG. 2A, IPsec VPN tunnel 15 mayhave assigned a local IP address 311 of bonded device VTI 31 and a peerIP address 331 of bonded VTI device 33.

3. Approaches for Selecting a Virtual Tunnel Interface

In an embodiment, datapath process 160 uses a VPN status function toindicate whether at least one slave VTI device implemented on gateway110 is up and operational and to indicate whether a route to the slaveVTI device exists. If one of a plurality of slave VPN tunnels fails butat least one other slave VPN tunnel remains operational, then the VPNtraffic is redirected to the operational slave VPN tunnel. For theclarity of description, it is assumed herein that both VPN 44 and VPN 54are operational.

In an embodiment, upon detecting a packet, a gateway selects a slave VTIfrom a plurality of slave VTIs of a bonded VTI implemented on thegateway. Once the gateway selects the slave VTI, the gateway relays thepacket onto an output port of the selected slave VTI, and then onto aslave VPN tunnel that backs up the selected slave VTI.

FIG. 2B is an example process for selecting a slave virtual tunnelinterface of a bonded virtual tunnel interface device. To select(element 210) a slave VTI of a bonded VTI implemented in the gateway,the gateway may use various approaches, such as applying a RR approach(element 211) to the packet, applying a load balancing approach (element212), or computing a hash value (element 213) from contents of innerheaders of the packet.

In an embodiment, to compute (element 213) a hash value, the gatewayuses contents of a portion 60 of packet 19. Portion 60 may include aninner IP header 26 and an inner TCP/UDP header 27. In addition toheaders 26-27, packet 19 may include an outer IP header 20, an ESPheader 21, an initialization vector 22, a data field 28, an ESP trailer29, and ESP authorization trail 30.

4. Selecting a Virtual Tunnel Interface

FIG. 3B is an example flow chart for selecting, by a packet sendinggateway, a virtual tunnel interface and selecting a VPN tunnel. If thegateway implements approach 213, described in FIG. 2B, then the gatewaydetermines a hash value. In an embodiment, a hash value for a packet maybe determined based on contents of inner headers of the packet. The hashvalues for different packet flows most likely will be different.Therefore, different slave VTIs most likely will be selected fordifferent flows.

In step 314, the gateway performs a lookup of available slave VTIsconfigured on a bonded VTI implemented on the gateway. Referring to FIG.2A, suppose that the available slave VTIs on gateway 110 include VTI 31Aand VTI 31B.

Also, in this step, load balancer 150, or an equal-cost multi-pathrouting (“ECMP”) process executed by virtual router 140, determineswhether the packet needs to be relayed onto VT1 31A or VTI 31B. Virtualrouter 140 may make that determination based on the hash value computedfrom contents of inner headers 26-27, and using an outcome of an RR/loadbalancing.

Upon determining that the packet needs to be relayed onto, for example,VTI 31A, the gateway, in step 316, relays the packed on an output portof VTI 31A to have the packet transmitted via VPN tunnel 44 that backsup VTI 31A. However, if the gateway determines that the packet needs tobe relayed onto VTI 31B, then the gateway relays the packet on an outputport of VTI 31B to have the packet transmitted via VPN tunnel 54 thatbacks up VTI 31B.

100631 In an embodiment, the approach circumvents a need for creatingmultiple BGP-over-IPsec sessions that otherwise would have to be createdfor each of the VPN tunnels established between slave VTIs of the peeredgateways. Furthermore, the approach supports firewalls without worryingabout asynchronous routing as all connection states are created on asingle interface.

5. Selecting a CPU

In an embodiment, mechanisms are provided for allowing a network driverto spread incoming traffic across multiple CPUs to increase efficiencyand processor cache utilization. The mechanisms may be implemented on apacket receiving side where the gateway selects a CPU from a pluralityof CPUs implemented in the gateway. The CPUs may be selected based on,for example, a load balance approach to allow balancing the usage of theCPU resources on the packet receiving gateway.

FIG. 4 is an example flow chart for selecting, by a packet receivinggateway, a CPU for a VPN packet. In step 404, upon detecting a packet onVTI 33A (or VTI 33B), a NIC implemented in gateway 110A tries toidentify an L4 header in the packet. The NIC also tries to identify inthe packet an L3 header. If the NIC finds both L4-L3 headers, then ahash value is determined based on the contents of the L4-L3 headers.However, if the NIC identifies in the packet only the L3 header, then ahash value is determined based on the contents of L3 header.

In step 406, based on the hash value, a particular CPU implemented ingateway 110A is selected. For example, the particular CPU may beselected from a plurality of CPUs 1, 2 and 3, depicted in FIG. 1.Selecting a particular CPU, from a plurality of CPUs, allows a networkdriver to spread incoming traffic across multiple CPUs and thus increasethe efficiency and processor cache utilization.

6. Implementation Mechanisms

The present approach may be implemented using a computing systemcomprising one or more processors and memory. The one or more processorsand memory may be provided by one or more hardware machines. A hardwaremachine includes a communications bus or other communication mechanismsfor addressing main memory and for transferring data between and amongthe various components of hardware machine. The hardware machine alsoincludes one or more processors coupled with the bus for processinginformation. The processor may be a microprocessor, a system on a chip(SoC), or other type of hardware processor.

Main memory may be a random-access memory (RAM) or other dynamic storagedevice. It may be coupled to a communications bus and used for storinginformation and software instructions to be executed by a processor.Main memory may also be used for storing temporary variables or otherintermediate information during execution of software instructions to beexecuted by one or more processors.

7. General Considerations

Although some of various drawings may illustrate a number of logicalstages in a particular order, stages that are not order dependent may bereordered and other stages may be combined or broken out. While somereordering or other groupings may be specifically mentioned, others willbe obvious to those of ordinary skill in the art, so the ordering andgroupings presented herein are not an exhaustive list of alternatives.Moreover, it should be recognized that the stages could be implementedin hardware, firmware, software or any combination thereof.

The foregoing description, for purpose of explanation, has beendescribed regarding specific embodiments. However, the illustrativeembodiments above are not intended to be exhaustive or to limit thescope of the claims to the precise forms disclosed. Many modificationsand variations are possible in view of the above teachings. Theembodiments were chosen to best explain the principles underlying theclaims and their practical applications, to thereby enable othersskilled in the art to best use the embodiments with variousmodifications as are suited to the uses contemplated.

Any definitions set forth herein for terms contained in the claims maygovern the meaning of such terms as used in the claims. No limitation,element, property, feature, advantage or attribute that is not expresslyrecited in a claim should limit the scope of the claim in any way. Thespecification and drawings are to be regarded in an illustrative ratherthan a restrictive sense.

What is claimed is:
 1. A computer-implemented method for using virtualtunnel interface teaming to achieve load balance and redundancy invirtual private networks (“VPNs”), the method comprising: receiving, bya gateway, configuration data from a control plane; based on theconfiguration data, configuring on the gateway a bonded virtual tunnelinterface (“bonded VTI”) having a plurality of slave virtual tunnelinterfaces (“slave VTIs”); configuring a plurality of VPN tunnelsbetween the plurality of slave VTIs configured on the gateway and aplurality of slave VTIs configured on a remote gateway; configuring anIPsec VPN tunnel between the bonded VTI configured on the gateway and acorresponding bonded VTI configured on the remote gateway; logicallycombining the plurality of VPN tunnels into the IPsec VPN tunnel; andenabling communications of IPsec VPN traffic via the IPsec VPN tunnel.2. The computer-implemented method of claim 1, further comprising: basedon the configuration data, configuring a Border Gateway Protocol('BGP″)-over-IPsec session between the bonded VTI configured on thegateway and a corresponding bonded VTI configured on the remote gateway;and wherein the BGP-over-IPsec session comprises a first IP addressassigned to the bonded VTI configured on the gateway and a second IPaddress assigned to the bonded VTI configured on the remote gateway. 3.The computer-implemented method of claim 2, wherein the IPsec VPN tunnelcorresponds to the BGP-over-IPsec session; and wherein theBGP-over-IPsec session is dynamically updated using the BGP.
 4. Thecomputer-implemented method of claim 3, further comprising: as theBGP-over-IPsec session is dynamically updated using updated routinginformation provided by the BGP, updating a configuration of the IPsecVPN tunnel using the updated routing information.
 5. Thecomputer-implemented method of claim 1, further comprising: upondetecting a packet: selecting a particular slave VTI, of the pluralityslave VTIs configured on the gateway; selecting a particular VPN tunnel,from the plurality of VPN tunnels, that backs up the particular slaveVTI; generating an encapsulated packet by encapsulating the packet atleast with one or more headers comprising underlay IP addresses of theparticular VPN tunnel; and relaying the encapsulated packet onto anoutput port of the particular slave VTI to enable transmission of theencapsulated packet to the remote gateway.
 6. The computer-implementedmethod of claim 5, wherein the particular slave VTI is selected for thepacket based on any approach of: a round-robin approach, a loadbalancing approach, or a hash-value-based approach.
 7. Thecomputer-implemented method of claim 6, wherein upon receiving theencapsulated packet, the remote gateway selects a particular CPU, from aplurality of CPUs implemented in the remote gateway, for theencapsulated packet.
 8. One or more non-transitory computer-readablestorage media storing one or more computer instructions which, whenexecuted by one or more processors, cause the one or more processors toperform: receiving, by a gateway, configuration data from a controlplane; based on the configuration data, configuring on the gateway abonded virtual tunnel interface (“bonded VTI”) having a plurality ofslave virtual tunnel interfaces (“slave VTIs”); configuring a pluralityof VPN tunnels between the plurality of slave VTIs configured on thegateway and a plurality of slave VTIs configured on a remote gateway;configuring an IPsec VPN tunnel between the bonded VTI configured on thegateway and a corresponding bonded VTI configured on the remote gateway;logically combining the plurality of VPN tunnels into the IPsec VPNtunnel; and enabling communications of IPsec VPN traffic via the IPsecVPN tunnel.
 9. The one or more non-transitory computer-readable storagemedia of claim 8, storing additional instructions which, when executedby the one or more processors cause the one or more processors toperform: based on the configuration data, configuring a Border GatewayProtocol ('BGP″)-over-IPsec session between the bonded VTI configured onthe gateway and a corresponding bonded VTI configured on the remotegateway; and wherein the BGP-over-IPsec session comprises a first IPaddress assigned to the bonded VTI configured on the gateway and asecond IP address assigned to the bonded VTI configured on the remotegateway.
 10. The one or more non-transitory computer-readable storagemedia of claim 9, wherein the IPsec VPN tunnel corresponds to theBGP-over-IPsec session; and wherein the BGP-over-IPsec session isdynamically updated using the BGP.
 11. The one or more non-transitorycomputer-readable storage media of claim 10, storing additionalinstructions which, when executed by the one or more processors causethe one or more processors to perform: as the BGP-over-IPsec session isdynamically updated using updated routing information provided by theBGP, updating a configuration of the IPsec VPN tunnel using the updatedrouting information.
 12. The one or more non-transitorycomputer-readable storage media of claim 8, storing additionalinstructions which, when executed by the one or more processors causethe one or more processors to perform: upon detecting a packet:selecting a particular slave VTI, of the plurality slave VTIs configuredon the gateway; selecting a particular VPN tunnel, from the plurality ofVPN tunnels, that backs up the particular slave VTI; generating anencapsulated packet by encapsulating the packet at least with one ormore headers comprising underlay IP addresses of the particular VPNtunnel; and relaying the encapsulated packet onto an output port of theparticular slave VTI to enable transmission of the encapsulated packetto the remote gateway.
 13. The one or more non-transitorycomputer-readable storage media of claim 12, wherein the particularslave VTI is selected for the packet based on any approach of: around-robin approach, a load balancing approach, or a hash-value-basedapproach.
 14. The one or more non-transitory computer-readable storagemedia of claim 13, wherein upon receiving the encapsulated packet, theremote gateway selects a particular CPU, from a plurality of CPUsimplemented in the remote gateway, for the encapsulated packet.
 15. Anedge service gateway implemented in a computer network and configured toimplement virtual tunnel interface teaming approach to achieve loadbalance and redundancy in virtual private networks (“VPNs”), the edgeservice gateway comprising: one or more processors; one or more memoryunits; and one or more non-transitory computer-readable storage mediastoring one or more computer instructions which, when executed by theone or more processors, cause the one or more processors to perform:receiving, by a gateway, configuration data from a control plane; basedon the configuration data, configuring on the gateway a bonded virtualtunnel interface (“bonded VTI”) having a plurality of slave virtualtunnel interfaces (“slave VTIs”); configuring a plurality of VPN tunnelsbetween the plurality of slave VTIs configured on the gateway and aplurality of slave VTIs configured on a remote gateway; configuring anIPsec VPN tunnel between the bonded VTI configured on the gateway and acorresponding bonded VTI configured on the remote gateway; logicallycombining the plurality of VPN tunnels into the IPsec VPN tunnel; andenabling communications of IPsec VPN traffic via the IPsec VPN tunnel.16. The edge service gateway of claim 15, storing additionalinstructions which, when executed by the one or more processers, causethe one or more processors to perform: based on the configuration data,configuring a Border Gateway Protocol ('BGP″)-over-IPsec session betweenthe bonded VTI configured on the gateway and a corresponding bonded VTIconfigured on the remote gateway; and wherein the BGP-over-IPsec sessioncomprises a first IP address assigned to the bonded VTI configured onthe gateway and a second IP address assigned to the bonded VTIconfigured on the remote gateway.
 17. The edge service gateway of claim16, wherein the IPsec VPN tunnel corresponds to the BGP-over-IPsecsession; and wherein the BGP-over-IPsec session is dynamically updatedusing the BGP.
 18. The edge service gateway of claim 17, storingadditional instructions which, when executed by the one or moreprocessers, cause the one or more processors to perform: as theBGP-over-IPsec session is dynamically updated using updated routinginformation provided by the BGP, updating a configuration of the IPsecVPN tunnel using the updated routing information.
 19. The edge servicegateway of claim 15, storing additional instructions which, whenexecuted by the one or more processers, cause the one or more processorsto perform: upon detecting a packet: selecting a particular slave VTI,of the plurality slave VTIs configured on the gateway; selecting aparticular VPN tunnel, from the plurality of VPN tunnels, that backs upthe particular slave VTI; generating an encapsulated packet byencapsulating the packet at least with one or more headers comprisingunderlay IP addresses of the particular VPN tunnel; and relaying theencapsulated packet onto an output port of the particular slave VTI toenable transmission of the encapsulated packet to the remote gateway.20. The edge service gateway of claim 19, wherein the particular slaveVTI is selected for the packet based on any approach of: a round-robinapproach, a load balancing approach, or a hash-value-based approach.